Holding register read error when trying to set up the loader as a dynamic code via async serial server?

[nildude]

Hi fellows,

I am a newbie to modbus and programming the ascynio package. I am able to get my application to send data via modbus when I am sending "static data", however, when I am trying to crate a dynamic data store, I am getting this error message below that I am not able to decipher? Can you kindly give any suggestions as to what is going on (Thank you!).

2023-04-04 11:33:59,255 MainThread ERROR logging :114 Exception response Exception Response(131, 3, SlaveFailure)
2023-04-04 11:33:59,256 MainThread DEBUG logging :102 send: [Exception Response(131, 3, SlaveFailure)]- b'01830440f3'
2023-04-04 11:33:59,256 MainThread DEBUG logging :102 Frame - [b'\x01\x03\x00\x04\x00\x02\x85\xca'] not ready
2023-04-04 11:33:59,632 MainThread DEBUG logging :102 Handling data: 0x1 0x3 0x0 0x6 0x0 0x2 0x24 0xa
2023-04-04 11:33:59,633 MainThread DEBUG logging :102 Getting Frame - 0x3 0x0 0x6 0x0 0x2
2023-04-04 11:33:59,634 MainThread DEBUG logging :102 Factory Request[ReadHoldingRegistersRequest': 3]
2023-04-04 11:33:59,634 MainThread DEBUG logging :102 Frame advanced, resetting header!!
2023-04-04 11:33:59,634 MainThread DEBUG logging :102 validate: fc-[3] address-7: count-2
2023-04-04 11:33:59,635 MainThread ERROR logging :114 Datastore unable to fulfill request: 'coroutine' object has no attribute 'validate'; Traceback (most recent call last):
File "/usr/local/lib/python3.9/dist-packages/pymodbus/server/async_io.py", line 267, in execute
response = request.execute(context)
File "/usr/local/lib/python3.9/dist-packages/pymodbus/register_read_message.py", line 151, in execute
if not context.validate(self.function_code, self.address, self.count):
File "/usr/local/lib/python3.9/dist-packages/pymodbus/datastore/context.py", line 81, in validate
return self.store[self.decode(fc_as_hex)].validate(address, count)
AttributeError: 'coroutine' object has no attribute 'validate'

From other searches it states that it might be related to reset of the register counter? I am just not seeing the issue in my standard code example.

I am defining my data store function like below:

async def data_store_build(data1,data2, data3, data4):#, data5, data6, data7, data8, data9, data10):
    #while True:
      
        builder = BinaryPayloadBuilder(byteorder=Endian.Big, wordorder=Endian.Big)
        builder.add_32bit_float(data1) # [6/7]
        builder.add_32bit_float(data2)  # [8/9]
        builder.add_32bit_float(data3) # [10/11]
        builder.add_32bit_float(data4) # [12/13]
       # builder.add_32bit_float(data5) # [14/15]
       # builder.add_32bit_float(data6) # [6/7]
       # builder.add_32bit_float(data7)  # [8/9]
       # builder.add_32bit_float(data8) # [10/11]
       # builder.add_32bit_float(data9) # [12/13]
       # builder.add_32bit_float(data10) # [14/15]
        
        block = ModbusSequentialDataBlock(1, builder.to_registers())
        #print(f'Block written y = {y}, data1 = {data1}')
        return block
        await asyncio.sleep(1)

The server is packages like this:

async def run_async_server(block_in, port_in):
    """Run server."""
    txt = f"### start ASYNC server, listening on {port_in}"
    log.info(txt)
   
    # socat -d -d PTY,link=/tmp/ptyp0,raw,echo=0,ispeed=9600
    #             PTY,link=/tmp/ttyp0,raw,echo=0,ospeed=9600
    server = await StartAsyncSerialServer(
            context= ModbusServerContext(
                slaves=ModbusSlaveContext(
                    di=block_in, 
                    co=block_in, 
                    hr=block_in, 
                    ir=block_in), single=True),  # Data storage
            identity= ModbusDeviceIdentification(
                info_name={
                    "VendorName": "Pymodbus",
                    "ProductCode": "PM",
                    "VendorUrl": "https://github.com/riptideio/pymodbus/",
                    "ProductName": "Pymodbus Server",
                    "ModelName": "Pymodbus Server",
                    "MajorMinorRevision": version.short(),
                }),  # server identify
                
            timeout=250,  # waiting time for request to complete
            port=port_in,  # serial port
            # custom_functions=[],  # allow custom handling
            framer=ModbusRtuFramer,  # The framer strategy to use
            # handler=None,  # handler for each session
            stopbits=1,  # The number of stop bits to use
            bytesize=8,  # The bytesize of the serial messages
            parity="N",  # Which kind of parity to use
            baudrate=57600,  # The baud rate to use for the serial device
            # handle_local_echo=False,  # Handle local echo of the USB-to-RS485 adaptor
            # ignore_missing_slaves=True,  # ignore request to a missing slave
            # broadcast_enable=False,  # treat unit_id 0 as broadcast address,
            strict=True,  # use strict timing, t1.5 for Modbus RTU
            # defer_start=False,  # Only define server do not activate
          
        )
  
    return server

The server is set up like this:

if __name__ == "__main__":
    com_port_iot = '/dev/ttyUSB0'
    
    async def IoT2(com_port,data1,data2,data3,data4):
            server = run_async_server(data_store_build(data1,data2,data3,data4), com_port)
            task = asyncio.create_task(server)
            await asyncio.sleep(240)
            task.cancel()

  asyncio.run(IoT2(com_port_iot, 1, 2, 3, 4))

I am not able to share the full code, please let me know where I am doing something that is off.

Thank you and greatly appreciate your assistance.

Best regards,
Lars Henrik

[janiversen]

You should define the different register classes, have a look at our examples.

[nildude]

Thank you for getting back to me swiftly. I thought I did define the different register classes here:

slaves=ModbusSlaveContext(
                    di=block_in, 
                    co=block_in, 
                    hr=block_in, 
                    ir=block_in)

Any particular example you want me to look at? I started out from the serial server example?

Thank you.

Best regards,
Lars Henrik

[janiversen]

That example includes the setup of a datastore. I really cannot help you when you only provide partial code. If you have problems then isolate them in a small example which you can share. I hope you noted the slave failure, which might be your root problem.

[nildude]

Hi Jan,

I appreciate your response. Do you do paid consulting (Today!)?

I am trying to update my datastore and get the slave to broadcast the latest values. I hope to get something like this working (But it is not picking up the data store properly):

"""
Created on Wed Mar  8 23:15:13 2023

@author: user01
https://pymodbus.readthedocs.io/en/v3.1.1/source/example/server_async.html
"""

#!/usr/bin/env python3
"""Pymodbus asynchronous Server Example.

An example of a multi threaded asynchronous server.

usage: server_async.py [-h] [--comm {tcp,udp,serial,tls}]
                       [--framer {ascii,binary,rtu,socket,tls}]
                       [--log {critical,error,warning,info,debug}]
                       [--port PORT] [--store {sequential,sparse,factory,none}]
                       [--slaves SLAVES]

Command line options for examples

options:
  -h, --help            show this help message and exit
  --comm {tcp,udp,serial,tls}
                        "serial", "tcp", "udp" or "tls"
  --framer {ascii,binary,rtu,socket,tls}
                        "ascii", "binary", "rtu", "socket" or "tls"
  --log {critical,error,warning,info,debug}
                        "critical", "error", "warning", "info" or "debug"
  --port PORT           the port to use
  --store {sequential,sparse,factory,none}
                        "sequential", "sparse", "factory" or "none"
  --slaves SLAVES       number of slaves to respond to

The corresponding client can be started as:
    python3 client_sync.py
    
    https://python.hotexamples.com/examples/pymodbus.payload/BinaryPayloadBuilder/-/python-binarypayloadbuilder-class-examples.html
"""
import asyncio
import logging
#import os

#from examples.helper import get_commandline
from pymodbus.datastore import (
    ModbusSequentialDataBlock,
    ModbusServerContext,
    ModbusSlaveContext,
    ModbusSparseDataBlock,
)
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.framer.rtu_framer import ModbusRtuFramer
from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadBuilder

# --------------------------------------------------------------------------- #
# import the various client implementations
# --------------------------------------------------------------------------- #
from pymodbus.server import (
    StartAsyncSerialServer,
  #  StartAsyncTcpServer,
  #  StartAsyncTlsServer,
  #  StartAsyncUdpServer,
)
from pymodbus.version import version

FORMAT = ('%(asctime)-15s %(threadName)-15s'
          ' %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s')
logging.basicConfig(format=FORMAT)
log = logging.getLogger()
log.setLevel(logging.DEBUG)


builder = BinaryPayloadBuilder(byteorder=Endian.Big, wordorder=Endian.Big)

builder.add_32bit_float(11.34) # [6/7]
builder.add_32bit_float(22.34)  # [8/9]
builder.add_32bit_float(33.34) # [10/11]
builder.add_32bit_float(44.34) # [12/13]
builder.add_32bit_float(55.34) # [14/15]

block = ModbusSequentialDataBlock(0, builder.to_registers())


async def run_async_server(block_in, port_in):
    """Run server."""
    txt = f"### start ASYNC server, listening on {port_in}"
    log.info(txt)
   
    server = await StartAsyncSerialServer(
            context= ModbusServerContext(
                slaves=ModbusSlaveContext(
                    di=block_in, 
                    co=block_in, 
                    hr=block_in, 
                    ir=block_in), single=True),  # Data storage
            identity= ModbusDeviceIdentification(
                info_name={
                    "VendorName": "Pymodbus",
                    "ProductCode": "PM",
                    "VendorUrl": "https://github.com/riptideio/pymodbus/",
                    "ProductName": "Pymodbus Server",
                    "ModelName": "Pymodbus Server",
                    "MajorMinorRevision": version.short(),
                }),  # server identify
                
            timeout=250,  # waiting time for request to complete
            port=port_in,  # serial port
            # custom_functions=[],  # allow custom handling
            framer=ModbusRtuFramer,  # The framer strategy to use
            # handler=None,  # handler for each session
            stopbits=1,  # The number of stop bits to use
            bytesize=8,  # The bytesize of the serial messages
            parity="N",  # Which kind of parity to use
            baudrate=57600,  # The baud rate to use for the serial device
            # handle_local_echo=False,  # Handle local echo of the USB-to-RS485 adaptor
            # ignore_missing_slaves=True,  # ignore request to a missing slave
            # broadcast_enable=False,  # treat unit_id 0 as broadcast address,
            strict=True,  # use strict timing, t1.5 for Modbus RTU
            # defer_start=False,  # Only define server do not activate
            
          
        )
  
    return server
   


if __name__ == "__main__":
    print("Setting up server on port") 
    asyncio.run(run_async_server(block, '/dev/ttyUSB0'), debug=True)
    

    loop = asyncio.get_event_loop()

     # Run the task with a timeout of 120 seconds
    try:
         done, _ = loop.run_until_complete(asyncio.wait_for(run_async_server(block, '/dev/ttyUSB0'), timeout=120))
    except asyncio.TimeoutError:
         print('Task timed out after 120 seconds')

     # Close the event loop
    loop.close()

Thank you and as mentioned, I am willing to compensate you for jumping on a call or providing some solution.

Thank you. Thank you. Thank you.

Best regards,
Lars Henrik

[janiversen]

start by moving everything into asyncio.run() you are mixing multiple loops that is a nice recipe for disaster.

I do sometimes do paid consulting but not tonight.